P2138

Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation

Throttle control (drive-by-wire) Generic OBD-II High

What it means

P2138 means the two accelerator-pedal position signals (D and E) don't agree with each other. The ECM cross-checks these redundant signals to trust your pedal input, so when they disagree it can't tell how far you're pressing and drops the engine into reduced-power or idle-only mode. It's usually a failing pedal sensor or a wiring/connection fault, and it needs prompt repair.

High

Can I keep driving? Often not — a mismatch between the two pedal signals usually forces reduced-power/idle-only mode where the engine barely responds; repair before depending on the car.

Real-world scan data

Seen in

1,439

scans in the past year

Found in

0.2%

of scans

0.4%

of scans that found faults

Appears alongside · share of P2138 scans

P2127in 27.2% of scans

P2122in 22.4% of scans

P0113in 12.7% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Reduced power or 'limp' (failsafe) mode, sometimes idle-only
Little or no response when pressing the accelerator
Hesitation or surging

Common causes

Most likely first

Faulty accelerator pedal position sensor (D and E share one assembly)Likely
Wiring open, shorted, or chafed between the two sensor circuitsCommon
Poor connection or corrosion at the pedal sensor connectorCommon
5-volt reference or ground fault affecting one of the two signalsLess often
Failing ECM/PCMLess often

How to diagnose & fix

Work through it in order

Read freeze-frame data and record the D and E readings to see which one is off.
Inspect the accelerator pedal connector and wiring for damage, corrosion, or a poor pin.
With the key on, confirm a steady 5-volt reference and clean ground for both sensor circuits.
Watch both signals sweep smoothly and in proportion as the pedal is pressed; a flat or mismatched trace points to the sensor.
Replace the accelerator pedal position sensor assembly if the two elements don't track; suspect the ECM only after wiring is verified.

FAQ

Quick answers

Is it safe to drive with P2138?+

Not really — this fault usually locks the car into reduced power or idle-only, which is unsafe in traffic. Get it repaired before driving normally.

Can I just clear P2138?+

Clearing it won't help; because two signals disagree, the ECM re-checks constantly and the code returns almost immediately until the sensor or wiring is fixed.

Read & clear P2138 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX